Brush structure



y 1936- G. T. SOUTHGATE BRUSH STRUCTURE Original Filed Nov. 50, 1931 INVEN' TOR GEORGEII SOUTHGATE I"' A TORNEY Patented May 26, 1936 BRUSH STRUCTURE George T. Southgate, Forest Hills, N. Y., assignor, by mesne assignments, to Union Carbide and Carbon Corporation, a corporation of New York Continuation of application Serial No. 578,136, November 30, 1931. This application June 9, 1934, Serial No. 729,776

14 Claims. (Cl. 171-324) This invention relates to brush structures and constitutes a continuation of my application Serial No. 578,136, filed November 30, 1931, which has matured into Patent No. 2,003,056, issued May 28, 1935.

In some instances considerable friction is produced between a brush and the guide or holder therefor. This is particularly true in rotatable brush structures wherein the centrifugal force produced thereby during rotation imparts an outward movement of the brushes. This is objectionable because the brushes are forced against the inner surface of the outer walls of the brush holders, and this sets up considerable friction which must be overcome to urge effectively the brushes toward the current-collecting device.

Generally brushes are arranged to contact a current-collecting device at all times at a substantially uniform pressure. This is objectionable in rotatable brush structures when it is desired to employ a driving motor having a low starting torque, because the friction between the brush and the current-collecting device may be excessive during starting of the driving motor. thereby tending to prevent the motor coming up to normal speed.

An object of this invention is to provide a brush structure having a minimum amount of friction so that a brush is effectively urged toward a current-collecting device.

Another object of this invention is to provide a rotatable brush structure in which the brushes bear lightly on a current-collecting device during starting and are subsequently urged toward the current-collecting device at the desired pressure during normal operation.

These and other objects and advantages of my invention will become apparent as the following description proceeds, having reference to the accompanying drawing in which Figure 1 is a side elevation of a single brush structure, illustrating one embodiment of this invention, mounted on a rotatable member and having a brush bearing against a stationary current-collecting device;

Figure 2 is a longitudinal sectional view of the brush structure shown in Figure 1;

Figure 3 is a sectional view taken on line 33 of Figure 2, and

Figure 4 is a sectional view taken on line 4-4 of Figure 2.

Referring to the drawing, there is shown a current-collecting device, such as a commutator In, for example, comprising a plurality of segments II secured in any suitable manner to an annular member l2. The annular member I2 is supported within an enclosing housing 13 and may be disposed about a shaft 14 which may form part of the electrical device with which the commutator is associated.

In accordance with this invention each of the brushes l5 bearing against the commutator I0 is adapted to be slidably supported and urged toward the commutator by an independent brush structure unit B. As shown in Figure 1, the brush structure unit B comprises a brush holder l6 which is secured to a ring of suitable insulating material ll attached to the edge of an opening l8 that is formed in a plate member l9. The plate member l9 may be formed integral with a quill shaft disposed about the shaft l4, and may be driven at a constant speed in any suitable manner, as by a synchronous motor, for example.

Although only one brush structure unit B is shown in the drawing, it is to be understood that other such units may be provided in spaced relation on the plate member I!) for commutating the alternating current delivered to the commutator segments H; and other brush structure units (not shown) may be provided on the plate member [9 and electrically connected with the brush structure units B for delivering direct current to slip rings 2| and 22.

In order to reduce the friction normally produced between the outer surface of the brush l5 and the inner surface of the outer wall of the brush holder Hi, the cross sectional area of the brush holder I 6 is made slightly greater than that of the brush I5, and in the space thus provided there is disposed a plurality of rollers 23 mounted on a carriage 24. The carriage 24 is retained in position by the tension of a spring 25 having one end thereof connected to the carriage and the other end thereof connected to a pin 26 secured to the outer wall of the brush holder l6, and the peripheral surfaces of the rollers 23 contact the wall of the brush holder 16 and a face plate 21 secured to a portion of the side wall of the brush [5. It will be seen that the rollers 23 provide a point to point contact between the outer walls of the brush holder l6 and the face plate 21 and that the rollers 23 are freely movable lengthwise of the brush holder I6, the carriage upon which the rollers are mounted only being retained in position by the tension of the spring 25.

A member 28 in alignment with the brush holder l6 and arranged parallel to the shaft 14 is provided for urging the brush l5 toward the commutator l I. The member 28 extends through openings in opposite walls of a housing 29 which is secured to a bracket 29' forming part of the brush structure B. In order to insure free movement of the member 28 within the housing 29, a plurality of rollers 33 are mounted on a carriage 3] which is retained in position by a spring 32 having one end thereof secured to the carriage and the other end thereof secured to a wall of the housing 29. The rollers 39 contact one side of the member 28 and the inner surface of a wall of the housing 29 and allow substantially free movement of the member 28 to urge the brush l5 toward the commutator Hi.

The member 28 is actuated by a member 33 which extends through openings in the housing 29 and is arranged radially with respect to the. shaft I4 so as to be moved outwardly under the influence of the centrifugal force produced during rotation of the structure B and the rotatable plate member I9. The radially outward movement of the member 33 may be transmitted to the member 28 in any suitable manner. As shown, the members 28 and 33 are provided with toothed racks 34 and 35 arranged to engage pinions 36 and 31, respectively, which pinions are secured to a shaft 38 journaled in the housing 29. With this construction the centrifugal force produced by the rotation of the brush structure B and plate member I9 imparts a radially outward movement of the member 33 which effectively actuates the member 23 toward the brush l5 so asto urge the latter toward the commutator I 0.

In many instances it may be desirable to employ a motor having a low starting torque for driving the quill shaft 20 and rotatable brush structure mounted thereon. To insure that the brush friction will not prevent such a motor from coming up to normal speed, the brushes are arranged to bear lightly against the commutator l0 during the starting period of the motor by a spring 39 which is disposed about the radially movable member 33 at the outer end thereof. During the period the driving motor is coming up to normal speed, the spring 39 biases the radially movable member 33 outward sufiiciently to cause the member 28 to urge the brush I5 in light contact with the commutator l0. As the speed of the driving motor increases, the centrifugal force produced by the brush structure B forces the radially movable member 33 outward a greater distance; and when the driving motor reaches its normal speed, the centrifugal force produced will effectively urge the brush l5 against the commutator II] at the desired pressure.

The provision of the spring 39 also places all of the parts of the rotatable brush structure under a slight initial pressure, thus eliminating any noise which might otherwise occur during starting and stopping of the brush structure when the centrifugal force produced is not uniformly effective to maintain the brush l5 in contact with the commutator Ii).

While I have shown and described a particular embodiment of my invention, it will be apparent that many modifications may be made without departing from the spirit and scope thereof as set forth in the claims.

I claim:

1. A rotatable brush structure including a rotatable plate having at least one brush holder mounted thereon, said brush holder having an aperture to receive a brush for motion parallel with the axis of rotation of the rotatable plate; and means for moving the brush parallel to the axis of rotation comprising a member movable radially with respect to the axis of rotation under the influence of centrifugal force, a second member engaging the brush and movable parallel to the axis of rotation, and means for transmitting motion from said radially movable member to said brush engaging member.

2. Apparatus of the class described comprising the combination of a brush having a face plate, an apertured guide surrounding said brush, friction reducing members disposed between said face plate and said guide, a member engaging said brush, an apertured guide for said brush engaging member, and friction reducing members disposed between said brush engaging member and the guide therefor.

3. Apparatus of the class described comprising the combination of a plurality of commutator sectors arranged in a vertical plane, a rotatable plate arranged in a vertical plane near said commutator sectors, at least one brush holding structure mounted on said rotatable plate and insulated therefrom, said structure comprising a brush having a face plate. on the side away from the axis of rotation of said rotatable member, a brush guide, friction reducing members disposed between said face plate and an adjacent wall of said guide, centrifugally operated means for forcing said brush against said sectors during rotation of the rotatable member, and a spring cooperating with said centrifugally operated means for holding said brush against said sectors when the rotatable plate is stationary.

4. Apparatus of the class described comprising the combination of a plurality of commutator sectors arranged in a vertical plane, a rotatable plate arranged in a vertical plane near said sectors, at least one brush holding structure mounted on said rotatable plate and insulated therefrom, said brush structure comprising a brush mounted for movement parallel to the axis of rotation of said rotatable member, a member engaging said brush, a member mounted for movement radially of the axis of rotation, means for transmitting motion from said radially movable member to said brush engaging member, and means including a spring for forcing said radially movable member outwardly, said spring having a force greater than the weight of said radially movable member.

5. Apparatus of the class described comprising a brush having a face plate on one side thereof, an apertured guide for said brush, a movable member between said face plate and the wall of said guide adjacent thereto, said movable member being provided with rollers engaging said. face plate and said wall, means engaging one end of said brush and provided with a rack, a member movable at right angles to said brush engaging member and provided with a rack, and means engaging said racks for transmitting motion between said last mentioned members.

6. Rotatable brush structure including the combination of a rotatable member, means attached to said rotatable member for holding and guiding a brush, means for urging the brush toward a current collecting device, and means cooperating with said brush holding and guiding means and the brush and freely movable lengthwise of said guiding means for reducing the friction therebetween during rotation of the rotatable member to utilize effectively said means for urging the brush toward the current collecting device.

7. Rotatable brush structure comprising a rotatable member, means including a part attached to said rotatable member for holding and guiding a brush, means including a part adapted to contact the brush for urging the same toward a current-collecting device, means attached to said rotatable member for guiding said last mentioned part, and means including a plurality of rollers having the peripheral surfaces thereof contacting said brush urging part and the guiding means therefor for reducing the friction therebetween during rotation of the rotatable member.

8. Apparatus of the class described comprising the combination of a brush, an apertured guide for said brush having a cross-sectional area greater than that of the brush to provide a space between one side of said brush and a wall of said guide, a face plate secured to the side of said brush opposite the space, and means disposed in the space and contacting said face plate and the wall of said guide for reducing the friction between said guide and the brush as the latter is urged toward a current-collecting device.

9. Apparatus of the class described comprising the combination of a brush, an apertured guide for said brush having a cross-sectional area greater than that of the brush to provide a space between one side of said brush and a wall of said guide, a face plate secured to a portion of one side of said brush, and means including a plurality of rollers disposed in the space and having the peripheral surfaces thereof contacting said face plate and the wall of said guide for reducing the friction between said guide and the brush as the latter is urged toward a current-collecting device.

10. Apparatus of the class described comprising a stationary current-collecting device, a rotatable shaft disposed at right angles to said currentcollecting device and having a plate secured there.- to substantially parallel to to said current-collecting device, said plate having at least one opening, a brush structure attached to said plate at the opening and insulated therefrom, said brush structure comprising an apertured guide extending substantially parallel to said shaft and toward said current-collecting device, a brush disposed in said guide, said brush being of smaller cross sectional area than that of said guide to provide a space between one face of said brush and an adjacent wall of said guide, means including a plurality of rollers disposed in such space and having the peripheral surfaces thereof contacting the face of said brush and the adjacent wall of said guide, and means for urging said brush toward said current-collecting device.

11. Apparatus of the class described comprising the combination of rotatable means, means arranged parallel to the axis of rotation of said rotatable means and mounted thereon for holding and guiding a brush, means attached to said rotatable means including an element arranged radially of the axis of rotation of said rotatable means and having a resilient member cooperating therewith for urging the brush toward a currentcollecting device to bear lightly thereon, and centrifugally operable means attached to said rotatable means and associated with said element for further urging the brush toward said currentcollecting device during rotation of said rotatable means.

12. Rotatable brush structure comprising the combination of a rotatable member, a brush holder attached to said rotatable member and arranged parallel to the axis of rotation thereof, and means attached to said rotatable member including an element arranged radialy of the axis of rotation of said rotatable member and having a resilient member cooperating therewith for urging a brush toward a current-collecting device and for maintainng the same in light contact therewith, said element being movable and operative under the influence of centrifugal force to urge the brush toward the current-collecting device during rotation of said rotatable member.

13. Rotatable brush structure comprising the combination of rotatable means, means attached to said rotatable means and arranged parallel to the axis of rotation thereof for holding a brush, movable means in alignment with said brush holding means and adapted to contact the brush for urging the same toward a current-collecting device, and centrifugally operable means attached to said rotatable means including a movable element arranged radially of the axis of rotation of said rotatable means, said movable element being automatically operative during rotation of said rotatable means for actuating said movable brush urging means.

14. Rotatable brush structure according to claim 13, including a resilient member disposed about said element for actuating said movable brush urging means and causing the brush to bear lightly on the current-collecting device during the time the centrifugally operable means is not rendered operative.

GEORGE T. SOUTHGATE. 

